<div id="navigation">
  <h1>目录</h1>
  <ul class="nav sidenav">
<!--
    {% for post in site.posts  %}
      {% capture this_year %}{{ post.date | date: "%Y" }}{% endcapture %}
      {% capture this_month %}{{ post.date | date: "%B" }}{% endcapture %}
      {% capture next_year %}{{ post.previous.date | date: "%Y" }}{% endcapture %}
      {% capture next_month %}{{ post.previous.date | date: "%B" }}{% endcapture %}

      {% if forloop.first %}
        <li><a href="#year_{{this_year}}">{{this_year}}</a>
          <ul class="nav">
            <li><a href="#month_{{this_year}}_{{this_month}}">{{this_month}}</a></li>
      {% endif %}

      {% if forloop.last %}
            </ul>
          </li>
      {% else %}
        {% if this_year != next_year %}
            </ul>
          </li>
          <li><a href="#year_{{next_year}}">{{next_year}}</a>
            <ul class="nav">
              <li><a href="#month_{{next_year}}_{{next_month}}">{{next_month}}</a></li>
        {% else %}    
          {% if this_month != next_month %}
              <li><a href="#month_{{next_year}}_{{next_month}}">{{next_month}}</a></li>
          {% endif %}
        {% endif %}
      {% endif %}
    {% endfor %}
-->
  </ul>
</div>